The UAV is now widely used for reconnaissance. Characteristically small, inexpensive, and pilot-less (i.e., unmanned cockpit), the UAV is ideal for that purpose.
Notwithstanding its low cost, the UAV is not considered to be a disposable item; recovery is at least attempted after each mission. Recovery is relatively straightforward when the UAV is operating over land. In such situations, the UAV is simply brought down on a makeshift landing field. Recovery is considerably more challenging, however, when the UAV is operating at sea. Due to the constant sway, roll, pitch and yaw of a ship at sea, it is quite difficult to safely land a UAV on the deck of a ship. In fact, deck landings are rarely attempted.
One alternative to the deck landing is the water “landing,” wherein a UAV is simply ditched in the sea. This technique has its own drawbacks, including a reasonable likelihood of damage to the UAV and some risk to the recovery crew. A second alternative to a deck landing is to capture the UAV while it's still in flight.
U.S. Pat. No. 4,753,400 discloses a ship-mounted apparatus that recovers UAVs while they are in flight. The system disclosed in that patent includes a recovery net that is attached to a parachute. The net is also coupled, via a tow line, to a winch that is located on the deck of a ship. In use, the parachute floats the recovery net to a desired altitude for mid-air capture of the UAV. After capture, the recovery net and ensnared UAV are winched down to the deck.
The apparatus that is disclosed in U.S. Pat. No. 4,753,400 has several drawbacks. One drawback is that the apparatus disadvantageously requires a substantial amount of deck area. A second drawback is that a relatively labor-intensive untangling operation is required to free the UAV from the net. Furthermore, the relatively abrupt stop of a UAV in the recovery net can damage its fragile wings.
As a consequence, there is a need for a UAV recovery system that requires little deck space, enables rapid re-use of a UAV after recovery, and is less likely to damage a UAV than traditional recovery techniques.